The authors, researchers at the National University of Ireland and Leiden university, did research investigating emergent stimulus relations produced by match-to-sample tasks with compound samples and unitary comparisons. The study was a modified replication of the Markham and Dougher study (1993) and consisted of two experiments. Four adults participated in Experiment 1, and 12 6- to 11-year-old children in Experiment 2. Both experiments involved the same training and testing sequence: Training of four AB-C relations (A1B1-C1, A2B2-C1, A1B2-C2, A2B1-C2), followed by C-AB tests (symmetry) and BC-A or AC-B tests, C-D training (C1-D1, C2-D2), DC tests, D-AB tests (equivalence), and AD-B or BD-A tests. All 16 subjects demonstrated class-consistent C-AB and class-like AC-B or BC-A relations. Of these subjects, 15 also demonstrated class-consistent D-AB and class-like BD-A or AD-B relations.